Effect of air temperature on common bunt (Tilletia caries) infection in winter wheat

Abstract

During the period 1993–2006 experiments designed to study the peculiarities of common bunt infection in winter wheat were carried out in a nursery with artificial inoculation at the Lithuanian Institute of Agriculture. The effects of air temperature from sowing to resumption of vegetation were determined using correlation analysis on the infection level of common bunt in winter wheat. A significant correlation between the mean nursery infection and daily mean temperature had a maximum value on the 36th day (r=0.60) at a 30–190-day interval after sowing. The minimum value was detected on the 150th day (r = -0.65) at a 150–190-day interval after sowing. The calculation of multi-intervals of mean temperatures allowed us to highlight the actual influence of temperature on the final level of common bunt infection. Cross-comparison of 6 contrasting years indicated that the impact of post-sowing temperatures was low. This was proved in 1994, 1998, and 2006 with similar temperatures but considerable differences in final infection levels – 46.9, 6.8, and 80.9%, respectively. Of the 6 test years only post-sowing temperatures in the autumn of the year 2003 were unfavourable for initial infection. The mean infection level was low when heavy frosts occurred together with a thin snow cover in 1995 (8.6%), 1998 (6.8%), and 2004 (8.9%). A high infection level occurred when heavy frosts coincided with a thicker snow cover in 1994 (46.9%), 1999 (22.9%), and 2006 (80.9%).